In general, the detection of slow leaks, for example, in toilets, sinks or other valved water outlet device, are not detectable by human observation and may occur unobserved. It has been shown that a leak of one drop per second can result in a yearly waste of 10,000 liters of water. For apartment buildings with hundreds of toilets, for example, the potential economic impact of water waste is significant. In those geographical areas where water is scarce, the importance of conservation is equally important as the economic impact. Accordingly, a need exists for devices and systems to monitor, detect and, ideally, control leaks, including slow leaks.